1. Field of the Invention
The invention pertains to the use of an adsorbent for the removal of liquid, gaseous and/or dissolved constituents from a process stream.
2. Prior Art
The above use is generally known and widely employed in chemical engineering. One well-known example is the use of a column filled with activated carbon for the removal of, say, aromatic and/or chlorinated hydrocarbons from a process stream. Once the activated carbon in the column has become saturated, it is generally replaced by fresh activated carbon, while the saturated carbon is reactivated. Meanwhile it has been found that several synthetic adsorbents can be regenerated a number of times with, say, steam.
A major drawback to the known process is that it is susceptible to certain inorganic contaminants which are commonly found in very minute concentration, in, say, groundwater to be treated, such as compounds of iron, manganese, calcium, and magnesium which in themselves are not harmful and so do not need to be removed, yet which nevertheless, in the course of time, may lead to fouling of the adsorbent because a substantial part of its surface area will be covered with said contaminants. To overcome the aforementioned problem it has been proposed in WO 94/03249 that instead of particles having adsorbent properties, particles having extracting properties be used. The extracting particles having a particle size in the range of 0.1 to 10 mm have pores with a diameter of 0.01 to 50 μm with an extraction liquid immobilised therein.
Although better results can be achieved with these particles, especially after long-term use, than with the well-known adsorbents because of the extracting particles showing no tendency to fouling or a much lower one, the adsorption capacity of adsorbing materials, especially when the overall concentration of the constituents to be removed does not exceed more than about 100 ppm, as a rule is higher than that of the extracting synthetic particles described above. Consequently, a column containing adsorbents such as activated carbon can be much smaller in size than a column filled with extracting synthetic particles to achieve the same result. For that reason there is great need for an adsorbent which combines the advantages of a higher capacity and a lower tendency to fouling, such as is present in extracting synthetic particles.
The invention provides for the use of an adsorbent for the removal of liquid, gaseous and/or dissolved constituents from a process stream which obviates wholly or for the most part the problems which occur when using the known adsorbents.